A machine which can rapidly and automatically translate languages, particularly speech, has been sought for many years. However, even with the tremendous progress in computing, speech recognition and speech synthesis in recent years, such machines remain the stuff of dreams and fiction.
Considerable research has been carried out on computer systems for the automatic translation of text. Apart from a few very restricted applications (e.g. translation of weather forecasts), no product exists which can automatically produce accurate translations and hence replace human translators. The problems of translating speech are compounded by the errors of speech recognition, the additional information in intonation, stress etc and the inexactness of speech itself.
Unfortunately, existing text language translation packages are all deficient in some way or another and do not meet the requirements of a system translating speech-to-speech. Most such packages have been designed as an aid for professional translations, and produce outputs which have to be post-edited before being presentable in their target language. Most packages are either menu-driven and interactive or operate in a slow batch processing mode, neither of which is suitable for "real-time" speech operation. Translation packages also tend to be unreliable, as idioms and other exceptions can easily cause erroneous output: the user has no guarantee that the output is correctly translated. Existing systems are also very CPU intensive, making them inexpensive to run and hence unsuitable for many cost sensitive applications.